Because it is an Italian word, which is perhaps not as common a source for words as to have it ingrained into people’s brain, say compared to French.

But quite clearly there are lots of soft rules that should never be learned directly, but indirectly people do pick up (not only natives, I am not a native English speaker, yet I can probably guess an approximate pronunciation for unseen words that won’t be statistically too bad) — like how an ML model might do.